COVER STORY | NUCLEAR’S NEXT CHAPTER
Building for nuclear’s next chapter
More than two-thirds of the world’s operating reactors are over
30 years old but the issue of age is not the reactor or containment, it is the balance of plant electrical systems.
By Stuart Thompson, President, Electrification Service Division, ABB
history, not because reactors are failing, but because the systems around them are aging faster than most people realise, and the decisions we make in the next few years will shape their performance for decades to come. In the United States alone, roughly 90% of the nuclear
fleet has already renewed its operating license once, extending operations to 60 years, and driven by soaring electricity demand from data centres and industrial electrification, several operators are now pursuing subsequent renewals to 80 years, with regulators beginning to discuss what a century of operation would actually demand. This is a remarkable bet on an aging fleet, and it will only pay off if any modernisation is done in the right way.
As legacy equipment ages, spare parts grow scarce, manufacturers discontinue product lines, and specialised knowledge of vintage systems retires. Source: Shutterstock
THE GLOBAL DEBATE ABOUT NUCLEAR energy has become fixated on the wrong question. While politicians discuss the merits of building new plants and investors chase the promise of small modular reactors, more than two-thirds of the world’s 440-plus operating reactors are over 30 years old, according to the International Atomic Energy Agency (IAEA). More worryingly, the very electrical infrastructure keeping them alive is quietly approaching obsolescence at precisely the moment demand for nuclear power is surging once again. In reality, the engineers who keep these plants running don’t debate nuclear policy in conference rooms; they walk the floors of plants commissioned as far back as the 1970s. They are seeing firsthand what it means when switchgear has outlived its design life, when circuit breakers need replacing but spare parts are no longer available, and when protection systems that predate the smartphone by decades must be retrofitted for today’s operational demands. From that vantage point, what comes into view is a global fleet entering the most consequential period in its
16 | May 2026 |
www.neimagazine.com
It’s not the reactor. It’s everything around it. What most don’t fully appreciate is that the reactor vessel itself is rarely the life-limiting factor. The concrete containment, the pressure vessel, the primary loop: these are all engineered for extraordinary longevity. What ages first, and what creates the most acute operational risk, is the balance of plant, meaning the electrical distribution systems, the switchgear, the protection relays, the motor control centres, and the excitation systems. Much of this equipment was installed with a 25- to 40-year design life, and in plants now expected to run for two or three times that span, this simply doesn’t add up. The problem compounds itself in ways that are easy
to underestimate. As legacy equipment ages, spare parts grow scarce, manufacturers discontinue product lines, and specialised knowledge of vintage systems retires alongside the engineers who installed them. It is a generational handover that the IAEA estimates will see roughly one-third of the existing global nuclear workforce leave the industry by 2033. Eventually, operators will reach a point where maintaining obsolete equipment is less about cost and more about safety. And in nuclear, safety questions don’t wait for convenient budget cycles. This is precisely what unfolded at the Doel 4 nuclear power plant in Belgium. Commissioned in 1985 and originally scheduled for decommissioning at the end of 2025, the plant was granted a 10-year life extension
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